1. Field of the Invention
This invention relates to electrical terminations and particularly to such terminations which include an assembly for securing a nut in alignment with an aperture in a flat stab of an electrical switch for receipt of a screw which threads into the nut to fasten an electrical conductor to the flat stab.
2. Background of Information
Electrical switches, including circuit breakers, contactors, motor controllers, motor starters and switches without overload protection, often have flat stabs for connecting the switch to conductors of the electrical system in which the switch is used. Many types of terminal connections are used with such switches, but in a widely used simple connection a spade or eye termination on the electrical conductor is clamped to the stab by a screw passed through an aperture in the stab and secured by a nut. Flat conductors can be secured to the stab in a similar manner with the screw passing through an aperture in the flat conductor as well.
Typically, the stabs are protected within recesses in the switch housing which makes access difficult. For ease in making such connections, it is known to secure the nut to the stab in alignment with the aperture so that only the screw needs to be manipulated. In one such connection, the nut has an annular flange around the tapped hole which is press fit into the aperture in the stab to retain the nut. Thus, special nuts must be provided for each size aperture in the stabs. Also, the nut can be dislodged and dropped by excess pressure applied to the screw before the threads are fully engaged.
In another arrangement, a flat piece of copper and a steel nut are held in spaced relation with an aperture in the piece of copper aligned with the tapped hole in the nut by a flexible bridge along one edge to form a keeper which clips onto the stab. Maintaining alignment is difficult, and again, excess pressure on the screwdriver can displace the steel nut.
In yet another keeper arrangement, a thin piece of copper is bent to form a u-shaped clip with a top wall, an end wall and a bottom wall. A square nut with ears on opposite sides is retained within the u-shaped clip with its tapped hole aligned with holes in the top and bottom walls, and is at the same time prevented from turning, by tabs on the side edges near the free end of the bottom wall. Additional tabs bent down from the sides of the top wall engage the ears on the nut to space it from the top wall to make room for applying the clip to the stab with the stab between the nut and the top wall. The resilient sheet material used for the clip clamps the nut against the stab. One difficulty with this u-shaped spring clip is that excessive axial force on the screw driver bends the bottom wall downward so that the nut can not be engaged by the screw.
Another arrangement is disclosed in U.S. Pat. No. 5,493,085 in which a single piece of spring material is formed into a spring clip having a top wall with a central aperture in it, a pair of slotted side walls, an end wall and a bottom wall cantilevered from the bottom edge of the end wall. A flat nut fits in the pocket formed by the walls of the clip. The nut has projections on opposite sides for fitting in the slots in the side wall. The clip is adapted to slide onto the free end of a flat stab which is received in the pocket between the top wall of the clip and the nut, so the nut can be clamped against the stab.
There is a need for an improved spring clip for electrical connections for electrical terminals having flat stabs, which is easier and more economical to manufacture. There is a further need for such electrical connections which are easy to assembly with an electrical terminal and provide secure retention of a terminal nut in alignment with an aperture in the stab during engagement of the nut by the screw.
There is an additional need for an improved connection which is economical and is easily installed without the need for any special tools.